A knob for a gear lever of a motor vehicle has a useful and a decorative function. The knob covers rough edges of and a small cross sectional area end of the lever to prevent puncture wounds in accidents and provides a better grip for a user of the gear lever. However, the knob must be sufficiently decorative so as not to adversely affect the decor of the interior of the vehicle. Also, with the almost exclusive use of mass production techniques in the automobile industry, the knob must be relatively inexpensive to manufacture and easy to install.
The prior art knobs generally comprise a base and a cap which fits on the base. The cap and base are usually moulded from plastic and often at least one part is chrome plated for decorative purposes. The base is usually circular in cross-section and has an axial bore into which a gear lever passes in use. The cap usually has a stem depending from, or a circular recess defined in, one end. If the cap has a stem, the top end of the axial bore of the base is widened to receive the stem. Alternatively, if the cap has a recess, the top end of the base is pushed into the recess in the cap. To provide a good grip for a user of the gear lever, it is necessary that the cap and base do not rotate relative to each other or to the lever. Therefore, it is known to provide the co-acting portions of the cap and base with a longitudinal spline and corresponding recess which must be aligned by an operator during assembly of the knob. Aligning the spline and recess is a time consuming and labour intensive operation which is not conducive to mass production. Also during assembly, an end of the gear lever is pushed into the bore of the base and secured in it. The gear lever may be secured in the base by providing an interference fit of the gear lever in the bore or by coating the end of the gear lever with adhesive.
U.S. Pat. No. 2,182,007 discloses a knob in which the cap and base are provided with complementary threads. During assembly, the cap is screwed on the base. However, this is no more efficient in mass production than aligning a spline and recess. This patent also discloses a knob in which the cap and base are glued together. However, merely glueing the cap and base together does not provide a better solution as this operation is messy, time consuming and the glue often discolours the plastic from which the knob is moulded.
If the knob comprises more than two parts, the problems are magnified as during assembly of the knob, an operator is required to align two to three sets of splines and recesses or threads rather than a single set as with the two piece knobs.
An object of this invention is to provide a knob for a lever which is easily assembled, securely attached to the lever and the parts comprising the knob do not rotate relative one another.